In vertebrate animals, the heart is a hollow muscular organ having four pumping chambers: the left and right atria and the left and right ventricles, each provided with its own one-way valve. The natural heart valves are identified as the aortic, mitral (or bicuspid), tricuspid, and pulmonary, and are each mounted in an annulus comprising dense fibrous rings. The mitral and tricuspid valves have thread-like bands of fibrous tissue that attach to the valve at one end and to the papillary muscles at the other end.
Heart valve disease is a widespread condition in which one or more of the valves of the heart fails to function properly. Diseased heart valves may be categorized as either stenotic, wherein the valve does not open sufficiently to allow adequate forward flow of blood through the valve, and/or incompetent, wherein the valve does not close completely, causing excessive backward flow of blood through the valve when the valve is closed. Valve disease can be severely debilitating and even fatal if left untreated.
Various surgical techniques may be used to repair a diseased or damaged valve. One method for treating defective valves is through repair or reconstruction. One repair technique that has been shown to be effective in treating incompetence is annuloplasty, in which the effective size and/or shape of the valve annulus is modified by securing a repair segment, such as an annuloplasty ring, around the heart valve annulus. For example, the valve annulus may be contracted by attaching a prosthetic annuloplasty repair segment or ring to an interior wall of the heart around the valve annulus. The annuloplasty ring is designed to support the functional changes that occur during the cardiac cycle: maintaining coaptation and valve integrity to prevent reverse flow while permitting good hemodynamics during forward flow.
The annuloplasty ring typically comprises an inner substrate, often formed from a metal (such as stainless steel or titanium) or from a flexible material (such as silicone rubber or Dacron cordage), which is typically covered with a biocompatible fabric or cloth to allow the ring to be sutured to the heart tissue. Depending on a particular application, annuloplasty rings may be stiff or flexible, may be split or continuous, and may have a variety of shapes, including circular, D-shaped, C-shaped, saddle-shaped, and/or kidney-shaped. Examples are seen in U.S. Pat. Nos. 5,041,130, 5,104,407, 5,201,880, 5,258,021, 5,607,471, 6,187,040, and 6,805,710, the contents of which are incorporated herein by reference in their entirety. Many annuloplasty rings are formed in a plane, but some rings are generally non-planar. Such non-planar rings can be saddle-shaped, and/or bowed along various portions, such as being bowed along their anterior or straight side to conform to the desired shape of the annulus at that location.
In many diseased valves, the chordae tendineae are either ruptured, otherwise damaged, or of an improper length. When chordae tendineae are too long, too short, or otherwise damaged, the corresponding tricuspid or mitral valve to which they are attached typically may fail to close properly. For example, chordae tendineae which are ruptured or are too long allow a valve to prolapse, wherein one or more valve leaflets swing backward past their proper closed position. This can lead to regurgitation, which is the unwanted backflow of blood from a ventricle to an atrium resulting from imperfections in the valve. When the valve allows such backward flow into an atrium, the corresponding ventricle must pump progressively harder to circulate blood throughout the body, which in turn promotes congestive heart failure.
Repairing and/or replacing dysfunctional chordae tendineae has been performed for some time. The techniques for such repair are often complicated due to the difficulties in accessing the surgical site, in identifying the dysfunctional chordae tendineae, and in determining the proper length for the repaired and/or replacement chordae tendineae.
Another approach to valve repair involves surgical excision of all or a portion of one or more of the valve leaflets of the particular heart valve. In such a procedure, a damaged portion of a valve leaflet is excised, with the remaining portions of the valve leaflet stitched together to repair the opening created by the removal of the damaged portion. This procedure tightens the valve leaflet, which can prevent valve prolapse and thereby improve valve function. An example of such a procedure is a segmental resection of the mitral valve, wherein a prolapsing portion of a posterior leaflet is excised and the remaining portions sewed together to tighten the leaflet.
Quadrangular resection of the prolapsed area is a relatively common valve repair technique which has demonstrated excellent results. However, the technique is relatively complex and can require the surgeon to make numerous real-time decisions during the course of the procedure, including determining how large to make the resection, whether to perform an annulus plication to close the gap, etc.
The goal of mitral valve repair is to restore a good surface of coaptation to ensure satisfactory function of the valve. Because leaflet tissue is the primary component defining the surface of coaptation of the valve, it may be preferable to preserve as much as possible of the leaflet tissue, as opposed to resecting significant portions thereof. Preserving as much tissue as possible maintains anatomic and dynamic relationships, allowing for better distribution of forces and stresses on the valve components. However, in order to preserve the leaflet tissue, other aspects of the dysfunctional valve may have to be modified and/or treated, such as the shape of the valve annulus and any damaged chordae.
Accordingly, there has been a need for an improved apparatus, system, and method to repair dysfunctional heart valves, including mitral valves. The present invention satisfies one or more of these needs.